Hydroclimate variability and increase in several droughts revealed by a two-century record from tropical Andes in Peru

M. EUGENIA FERRERO; HUMANES-FUENTE, VICTOR; ÁLVARO GONZÁLEZ-REYES; ARIEL A. MUÑOZ; GABY INGA-GUILLEN; EVA LAYME-HUAMAN; JONATHAN BARICHIVICH; EDILSON J. REQUENA-ROJAS

Virtual

Conferencia; 6th Open Science Meeting PAGES; 2022

https://pastglobalchanges.org/

The Amazon basin plays an important role in the dynamics of the South American summer (SAMS). Almost half of the tributary rivers of the Amazon originate in the tropical Andes, which form a topographic barrier that produces a strong gradient in precipitation. Complete instrumental data and good representation of rainfall over the tropical Andes is available from 1979, but longer records are needed to understand precipitation variability and summer monsoon dynamics at various scales. In this sense, we developed the first annually-resolved precipitation reconstruction for the tropical Andes of Peru, based on tree-ring chronologies of Cedrela and Juglans species.The annual reconstruction (November to October) extends the short instrumental records back to 1817, and explains 68% of the total variance precipitation over the calibration period (1979-2007). An increase in the frequency occurrence of severe dry events (10th percentile) have been recorded for the last four decades in tropical Andean forests, in agreement with other paleoclimatic records in the region. The reconstruction also reveals the well-documented influence of ENSO on rainfall at interannual scales (~19% of total variance), and significant multidecadal variability of about 40 years (~13% of rainfall variability) related to the Atlantic Multidecadal Oscillation (AMO). Both oscillatory modes can explain dry and humid periods observed within the reconstruction and are likely associated with the negative trends of rainfall in the short instrumental records and the increased drought recurrence in recent decades.Our results highlight that montane tropical tree rings and high-resolution precipitation reconstruction can characterize and contribute to the interpretation of the interannual to multidecadal variability and identify remote forcings in the hydroclimate over the Andes and tropics of South America.